Public bug reported:
Upon booting into the newly upgraded ubuntu yakkety system I noticed
that the kernel option that grub listed was still linux-
image-4.4.0-21-generic. The system booted okay, but in aptitude linux-
image-4.4.0-21-generic was marked as obsolete (which lead to interesting
problems later
https://bugs.launchpad.net/ubuntu/+source/aptitude/+bug/1633897). That
is okay too, and while granted the linux-image-generic metapackage was
not installed, linux-image-4.8.x was not installed by the update/upgrade
process. What the upgrade process should probably do is upgrade to the
new kernel that comes with the particular flavour being upgraded to.